The present invention relates to a flexible intermediate bulk container (FIBC) for lifting, transportation and storage of bulk material. Such FIBC comprises a hose-shaped blank that is woven in such shape or is made from at least one piece of flat woven material joined together and having joints at its bottom and/or top ends. The FIBC also includes at least one lifting loop which might be formed from integral extensions of the container side walls, a filling opening and possibly also a liner.
The blank as defined herein can be made from round woven material or at least one piece of flat woven material joined together for forming at least one side joint or seam. Such joining together can for instance be performed subsequent to joining of the bottom and/or top joints.
FIBCs have been used for some time and have proved to be suitable for transportation, lifting and storage of bulk material such as granular fertilizer, ground and unground grain, Portland cement, coal, etc., in quantities of several hundred kilos per container.
The prior art reveals that the FIBCs are difficult to manufacture with a high degree of mechanization. Even relatively simple operations like cutting of the blank, folding and sewing of side and bottom seams are done manually. If the production of the container could be mechanized the manufacture costs would be reduced due to reduction in manual labor.
Previously known FIBCs for transportation of bulk material, e.g. from U.S. Pat. No. 4,269,247 (corresponding to NO U.S. Pat. No. 136,744), are made from a blank of flat woven fabric, and are formed by folding the blank at a transverse center line thereof and sewing the sides and the bottom. The middle section of the blank forms in the finished product a lifting loop which is an integral extension of the side walls. However, the container according to U.S. Pat. No. 4,269,247 was made with a squarish base by making gussets at opposite sides of the hose shaped blank before the base was sewn. The disadvantages of this construction are firstly that the containers are expensive to manufacture due to the long side seams and secondly that it is a difficult operation to make the gussets after the side seams have been made.
Further, there is known a container according to U.S. Pat. No. 4,136,723 (Norwegian Patent No. 138,134) which can be made from a round woven fabric. When such container is made from a round woven fabric, there will be no side seams. This container has a double base construction comprising one or two seams each having a length of 1/4 of the container circumference.
Neither of the two containers described in such U.S. patents are suitable for mechanized production and both such containers require a relatively large storage volume when empty.